Circuit Board for an Implantable Medical Device, and Method of Fabricating and Testing

ABSTRACT

Designs and methods of construction for a printed circuit board (PCB) in an implantable pulse generator (IPG) are disclosed which facilitate IPG PCB testing while also providing for protection of IPG circuitry in a simple and cost effective manner. The IPG PCB is formed as part of a larger test PCB, which includes an extender portion with traces routing nodes of interest in the IPG PCB to an edge connector. IPG electronics are mounted or soldered to the IPG PCB, and then such electronics are tested via the edge connector. The IPG PCB is then singulated from the extender portion in a manner leaving one or more PCB tabs at the severed edge of the PCB. The PCB tab(s) extend from the severed edge, and create an offset distance preventing traces severed and now exposed at the severed edge from contacting and potentially shorting to conductive structures in the IPG.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a non-provisional of U.S. Provisional Patent Application Ser.No. 61/902,062, filed Nov. 8, 2013, to which priority is claimed, andwhich is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to implantable medical devices, and moreparticularly to an improved design and method of construction andtesting of a circuit board for an implantable medical device.

BACKGROUND

Implantable stimulation devices deliver electrical stimuli to nerves andtissues for the therapy of various biological disorders, such aspacemakers to treat cardiac arrhythmia, defibrillators to treat cardiacfibrillation, cochlear stimulators to treat deafness, retinalstimulators to treat blindness, muscle stimulators to producecoordinated limb movement, spinal cord stimulators to treat chronicpain, cortical and deep brain stimulators to treat motor andpsychological disorders, and other neural stimulators to treat urinaryincontinence, sleep apnea, shoulder subluxation, etc. The descriptionthat follows will generally focus on the use of the invention within aSpinal Cord Stimulation (SCS) system, such as that disclosed in U.S.Pat. No. 6,516,227. However, the present invention may findapplicability with any implantable medical device or in any implantablemedical device system.

An SCS system typically includes an Implantable Pulse Generator (IPG),whose structure and construction is further described in U.S.Provisional Patent Application No. 61/874,194, entitled “Constructionfor an Implantable Medical Device Employing an Internal SupportStructure,” filed Sep. 5, 2013, which is incorporated herein byreference in its entirety. The IPG 10 of the '194 Application is shownin FIG. 1, which includes a biocompatible device case 30 that holds thecircuitry and battery 34 (FIG. 2) necessary for the IPG to function. TheIPG 10 is coupled to electrodes 16 via one or more electrode leads 14that form an electrode array 12. The electrodes 16 are carried on aflexible body 18, which also houses the individual signal wires 20coupled to each electrode 16. The signal wires 20 are also coupled toproximal contacts 22, which are insertable into lead connectors 24 fixedin a header 28 on the IPG 10, which header can comprise an epoxy forexample. Once inserted, the proximal contacts 22 connect to headercontacts 26 in the lead connectors 24, which header contacts 26 are inturn coupled by feedthrough pins 48 to circuitry within the case 30 aswill be explained subsequently. In the illustrated embodiment, there aresixteen electrodes 16 (E1-E16) split between two leads 14, although thenumber of leads and electrodes is application specific and therefore canvary. In a SCS application, electrode leads 14 are typically implantedon the right and left side of the dura within the patient's spinal cord.The proximal electrodes are then tunneled through the patient's tissueto a distant location, such as the buttocks, where the IPG case 30 isimplanted, at which point they are coupled to the lead connectors 24.

FIG. 2 shows perspective bottom and top sides of the IPG 10 with thecase 30 removed so that internal components can be seen. In particular,a battery 34, communication coil 40, and a printed circuit board (PCB)42, can be seen. As explained in the '194 Application, these componentsare affixed to and integrated using a rigid (e.g., plastic) supportstructure 38. Battery 34 in this example is a permanent,non-wirelessly-rechargeable battery. (Battery 34 could also berechargeable, in which case either coil 40 or another recharging coilwould be used to wirelessly receive a charging field that is rectifiedto charge the battery 34). The communication coil 40 enablescommunication between the IPG 10 and a device external to the patient(not shown), thus allowing bidirectional communication to occur bymagnetic induction. The ends of coil 40 are soldered to coil pins 44molded into the support structure 38 to facilitate the coil 40′seventual connection to circuitry on the IPG PCB 42. IPG PCB 42integrates the various circuits and electronics needed for operation ofthe IPG 10. As shown in FIG. 2, coil 40 is proximate to the bottom sideof the support structure 38 and case 30, while the IPG PCB 42 isproximate to the top side.

FIG. 3 shows a lead connector subassembly 95 for the IPG 10, whichincludes the lead connectors 24, the header contacts 26, feedthroughpins 48, and a feedthrough 32. The feedthrough 32 acts as a hermeticmeans for passing via the feedthrough pins 48 electrode signals betweenthe header contacts 26 (and ultimately electrodes 16) and the circuitryinternal to the case 30 on the IPG PCB 42. Lead connector subassembly 95can be formed by slipping the feedthrough pins 48 through thefeedthrough 32, soldering one end of the feedthrough pins 48 toappropriate header contacts 26 in the lead connectors 24, and solderingor brazing the feedthrough pins 48 in the feedthrough 32 in a hermeticmanner. Notice that the free ends of the feedthrough pins 48 are bent at90 degrees relative to the feedthrough 32, which facilitates connectionto the IPG PCB 42 as discussed subsequently. In this example, there aretwo rows of bent feedthrough pins 48, with the top row spaced by adistance d1, and the bottom row spaced by a distance d2, from a bottomsurface of the feedthrough 32, the relevance of which will be explainedlater.

Some of the construction steps of the IPG 10 are shown in FIGS. 4A and4B, and because these steps are disclosed in the '194 Application, theyare only briefly summarized here. Construction begins by affixing abattery terminal face 57 of the battery 34 to the support structure 38,using double sided tape 58 for example. The combined support structure38 and battery 34 is then placed in an assembly jig 94 as shown in crosssection in FIG. 4B. Next, the lead connector subassembly 95 (FIG. 3) ispositioned within the jig 94. Like the feedthrough pins 48 in the leadconnector assembly 95, the battery terminals 46 are bent at 90 degreesrelative to the battery terminal face 57, and so both the feedthroughpins 48 and battery terminals 46 are now pointing upward when placed inthe jig 94. Next, the IPG PCB 42—preferably pre-fabricated with itselectrical components—is affixed to the top side of the supportstructure 38. In this regard, IPG PCB 42 includes coil solder pin holes50, battery terminal solder holes 52, feedthrough pin solder holes 54,and support structure mounting holes 56, which are respectively slippedover the upward-pointing coil pins 44 (in the support structure 38),feedthrough pins 48, battery terminals 46, and mounting pins 88 of thesupport structure 38. The coil pins 44, feedthrough pins 48, batteryterminals 46 are then soldered to the coil solder pin holes 50,feedthrough pin solder holes 54, and battery terminal solder holes 52respectively to electrically couple them to the IPG PCB 42. Thereafter,and as explained in the '194 Application, the resulting IPG subassembly92 is then placed in its case 30, which is welded together and to thefeedthrough 32, and the header 28 is then added to complete IPG 10'sconstruction.

The inventors consider it desirable to electrically test the IPG PCB 42before it is attached to the support structure 38 and electricallycoupled to the battery 34 and feedthrough pins 48, and sealed within itscase 30, and techniques are disclosed for doing so, which also involveimproved designs and methods of constructing the IPG PCB 42.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an Implantable Pulse Generator (IPG) and the manner inwhich electrode leads are affixed to the IPG in accordance with theprior art.

FIG. 2 shows bottom and top views of the IPG with its case removed inaccordance with the prior art.

FIG. 3 shows a feedthrough subassembly used in the construction of theIPG in accordance with the prior art.

FIGS. 4A and 4B show certain steps in the assembly of the IPG inaccordance with the prior art.

FIG. 5 shows an improved method of manufacturing and testing a printedcircuit board (PCB) for use in the IPG, in which the IPG PCB is formedwith an extender PCB portion that can interface with a test system.

FIG. 6 shows the IPG PCB after testing and after it is severed from theextender PCB, and shows severed traces at its severed edge, and PCB tabsformed in the severed edge to prevent shorting of the severed traces.

FIGS. 7 and 8 show the severed IPG PCB in relation to a feedthrough ofthe IPG, and shows how the PCB tabs prevent shorting of the severedtraces to the feedthrough.

FIG. 9 shows an alternative formation for the IPG PCB having a recessincluding the severed traces, and shows more generally how such recessprevents shorting of the severed traces to a generic conductivestructure.

DETAILED DESCRIPTION

Designs and methods of construction for a printed circuit board (PCB) inan implantable pulse generator (IPG) are disclosed which facilitate IPGPCB testing while also providing for protection of IPG circuitry in asimple and cost effective manner. The IPG PCB is formed as part of alarger test PCB, which includes an extender portion with traces routingnodes of interest in the IPG PCB to an edge connector. IPG electronicsare mounted or soldered to the IPG PCB, and then such electronics aretested via the edge connector. The IPG PCB is then singulated from theextender portion in a manner leaving one or more PCB tabs at the severededge of the PCB. The PCB tab(s) extend from the severed edge, and createan offset distance preventing traces severed and now exposed at thesevered edge from contacting and potentially shorting to conductivestructures in the IPG, such as a feedthrough.

The inventors consider it desirable to electrically test the IPG PCB 42before it is attached to the support structure 38 and electricallycoupled to the battery 34 and feedthrough pins 48, and sealed within itscase 30, as explained earlier (FIGS. 4A and 4B). Such testing can bedifficult given the relatively small size of IPG PCB 42, which must fitinside the small case 30 of the IPG 10, and which must accommodate theprimary battery 34. Even though difficult to test because of its size,such testing of the IPG PCB 42 at this stage is important, as itscomponents can be easily damaged, particularly if the IPG PCB 42 ishandled by assembly technicians.

FIG. 5 shows one means of fabricating the IPG PCB 42 in a manner tofacilitate its testing prior to connection with other IPG components. Asshown, the IPG PCB 42 is formed as part of a larger test PCB 102, whichincludes an extender PCB portion 104 having an edge connector 106composed of contacts 106 a coupled to various PCB traces 108. Traces 108also couple to various nodes of interest in the IPG PCB portion 42 ofthe test PCB 102. The extender PCB 104 is preferably significantlylarger in area than the size of the IPG PCB 42 (e.g., at least twice thearea), and unlike the IPG PCB 42 has no electronic devices mounted toit, which facilitates easier handling of the IPG PCB 42 during testing,as an assembly technician can touch the extender PCB 104 without fear ofdamaging the electrical components otherwise mounted to the IPG PCB 42.

The edge connector 106's contacts 106 a are of standard size and pitchto meet with corresponding contacts in an edge connector socket 112coupled to a test system 110, which test system 110 can be of manydifferent types used by a manufacturer. In one example, edge connector106 and socket 112 comprise 80 pins, with 40 contacts 106 a on the topand bottom of the extender PCB 104 (and in the socket 112), although notall of these pins would necessarily be used.

In one example, the test PCB 102, and hence the IPG PCB 42 and extenderPCB 104, comprise a two-layer PCB in which two layers of conductivetraces can be formed. However, this is not strictly necessary, and thenumbers of layers needed in test PCB 102 will largely be dictated by thenumber of layers needed to interconnect the electrical components on IPGPCB 42. Additional layers needed by the IPG PCB 42, but not necessary toform traces 108 connecting the edge connector 106 with nodes of interestin the IPG PCB 42, may simply be unused in the extender PCB 104.

Thus, the electronic components needed to implement the functionality ofthe implantable medical device of the IPG PCB 42 (IPG 10) can be surfacemounted or otherwise soldered to the IPG PCB 42 portion of the test PCB102 in standard fashion, and then the edge connector 106 of the extenderPCB 104 portion of the test PCB 102 can be inserted in the socket 112associated with the test system 110 to test the IPG PCB 42 electronics.

As discussed above, nodes of interest in the IPG PCB 42 are routed viatraces 108 to the edge connector 106 to allow such testing to occur. Forexample, the test system 110 can provide reference voltages to the nodeson IPG PCB 42 where the positive (Vbat) and negative (GND) batteryterminals 46 will eventually be coupled, i.e., to battery terminalsolder holes 52. As well as providing power to operate the IPG PCB 42during the test, the test system 110 can also monitor the current drawnfrom node Vbat to verify whether significant leakage current is beingdrawn by the IPG PCB 42 indicative of a defect.

Traces 108 can also be connected to the electrode nodes (Ex) on the IPGPCB 42, i.e., to the feedthrough pin solder holes 54 to which thefeedthrough pins 48 will eventually be connected, allowing these nodesto be coupled to the IPG electrodes 16. This is useful for example toallow the test system 110 to make sure the electrode electronics on IPGPCB 42 are not short or open circuited.

Other nodes of interest in the IPG PCB 42 may be routed via traces 108as well, such as various bus signals on the IPG PCB 42 including control(C) and address/data (A/D) signals, which the tester can use to activateor monitor various modes of operation of the IPG PCB 42 circuitry. Othernodes of interest which may be routed include clock signals, other powersupply or reference voltages, the nodes where the coil 40 willeventually be connected, i.e., to coil solder pin holes 50, etc. Thesignals shown in FIG. 5 are thus merely exemplary, and in an actualimplementation many other nodes in IPG PCB 42 can be activated and/ormonitored by the test system 110 via traces 108.

Note that the traces 108 can pass anywhere between the IPG PCB 42 andthe extender PCB 104, except in the location of PCB tabs 130, whosefunction is explained further below. Preferably, the traces 108 passthrough a portion 132 between the two PCB tabs 130 that are shown, butthis is not strictly necessary, and some traces are shown passingthrough portions 134 on the outsides of the PCB tabs 130.

After electronic testing is completed, and if proper operation of theIPG PCB 42 is confirmed, the IPG PCB 42 is singulated from the PCBextender 104 along sever line 114, and the PCB extender 104 portion oftest PCB 102 can then be disposed of. In one example, a ComputerNumerical Control (CNC) router or milling machine is used to cut (e.g.,saw) the IPG PCB 42 from the extender PCB 104, with a Computer AidedDesign (CAD) file used to guide the router's cutting element along severline 114 so as to define the shape of the PCB tabs 130. Other methods ofsingulating the IPG PCB 42 may also be used, such as manual breaking,v-score shearing, nibbling, punching, etc. Note that while the severline 114 may be perforated or scored on the test PCB 102, this is notstrictly necessary, particularly if cutting is used for singulation.

FIG. 6 illustrates the IPG PCB 42 after singulation, and in particularshows sever line 114 in cross section, i.e., along the severed edge 114′of the IPG PCB 42. Because traces 108 cross sever line 114, they toowill be severed by the singulation process, and thus are exposed (notinsulated) in cross section 108′ at severed edge 114′. (The severedtraces 108′ are exaggerated in size, and assume only a single level PCB42). The severed traces 108′ at the severed edge 114′ of IPG PCB 42 areexposed, and thus could short circuitry connected to such nodes on theIPG PCB 42, particularly if sever line 114 is cut in a rough mannerallowing a severed trace 108′ to protrude from the severed edge 114′, asshown in the dotted-lined circle.

Shorting of the severed traces 108′ is especially concerning for thedesign of IPG 10 given the proximity of severed edge 114′ of IPG PCB 42to the feedthrough 32, as shown in FIG. 7. Note that the plane of IPGPCB 42 is perpendicular to the bottom surface of the feedthrough 32,such that severed edge 114′ of the IPG PCB 42 is parallel with, andclose to, this surface. Because the feedthrough 32 is conductive andwelded to the case 30, and because the case 30 is typically grounded bythe IPG 10 (or at least set to a fixed potential, as it too can be usedas an electrode 16), severed traces 108′ that touch the feedthrough 32could adversely affect the circuitry on IPG PCB 42 connected to suchtraces. Even if severed traces 108′ do not touch the feedthrough 32during manufacturing, they could do so later (even after implantation ina patient), especially considering that the IPG 10 is subject tomechanical shock and vibration and thermal expansion, which can causethe components in the IPG 10 to move with respect to each other.Additionally, unwanted conductive particulates within the IPG's case 30could eventually lodge between the severed traces 108′ and thefeedthrough 32, causing a short.

While an insulator could be applied to the severed edge 114′ to coverthe severed traces 108′, such as additional manufacturing step is notdesired, as it would raise the risk of damaging the IPG PCB 42 orintroducing new defects.

Instead, and in accordance with an aspect of the invention, at least onePCB tab 130 is provided along the severed edge 114′ of the side of theIPG PCB 42, and two such tabs 130 are shown in FIG. 7. The PCB tab(s)130 guarantee that an offset distance will maintained between thesevered traces 108′ and the feedthrough 32, which offset distance isdesigned to be significantly larger than the expected length of severedtraces 108′ protruding from the severed edge 114′, and significantlylarger than the size of any unwanted particulates that might be presentin the IPG 10. Said differently, severed traces 108′ at the severed edge114′ are recessed by the offset distance with respect to the PCB tab(s)130, thus preventing the exposed severed traces 108′ from contacting thefeedthrough 32. Conveniently, and preferably, the shape of the PCBtab(s) 130 can be defined during the singulation process by designingthe shape of sever line 114 accordingly.

Because the particular concern for IPG 10 is the shorting of severedtraces 108′ to the feedthrough 32, the PCB tabs 130 are located near tothe ends of the feedthrough 32 along its length as shown in FIG. 7,although this is not strictly necessary. In other IPG designs, thelocation of the PCB tab(s) 130 along the severed edge 114′ may changedepending on the position of the components in the IPG, and inaccordance with the isolation that is desired between the severed traces108′ and other conductive structures. One or more than two PCB tabs 130may be provided along severed edge 114′.

The operation of PCB tab(s) 130 are shown in further detail in themagnified view of FIG. 8. Ideally, the feedthrough 32 would normallyreside at a certain distance, w, from the portion 132 of the severededge 114′ between the two tabs 130 (only one shown). However, thisdistance w is difficult to guarantee because it is affected bymanufacturing tolerances, such as the distances d1 and d2 between thebent feedthrough pins 48 and the bottom surface of the feedthrough 32(see FIG. 3). Such distances d1 and/or d2 may be shorter or longerdepending on where the feedthrough pins 48 are bent, and can vary if theangle to which they are bent is not reliably constant. As a result, d1and/or d2 can vary, and thus when the bent feedthrough pins 48 areplaced through feedthrough pin solder holes 54 during IPG 10 assembly,the distance w can likewise vary. Should distance w be unusually smallfor a given IPG 10, and should a length y of a severed trace 108′ beusually long, there is a risk that that trace 108′ would short to thefeedthrough 32.

PCB tab(s) 130 prevent this from occurring. Notice that the PCB tabs 130extend perpendicularly from the severed edge 114′ by an offset distanceof x, which distance x is designed to be larger than a longest expectlength y of any severed trace 108′ or unwanted particulate. Thisrecesses the severed traces 108′, and guarantees that the distance wbetween the severed traces 108′ and the feedthrough 32 will never besmaller than x, and thus w will always be greater than y. As a result,no severed trace 108′ can touch the feedthrough 32. Distance x in oneexample is 0.005 inches (5 mils).

If d1 and/or d2 are unusually large, the natural resting position of thefeedthrough 32 relative to the IPG PCB 42 may be such that thefeedthrough 32 does not touch the surface of the PCB tab(s) 130. Inother words, w would be bigger than x, and a gap may exist between thefeedthrough 32 and the top of the PCB tab(s) 130 as shown, whichcondition does not raise the risk of shorting the severed traces 108′.However, if d1 and/or d2 are unusually small, the feedthrough 32 wouldcontact the top of the PCB tab(s) 130, thus limiting w to x. If w isnaturally small by virtue of how the feedthrough pins 48 are bent,offset distance x may force the ends of the feedthrough pins 48 to bendin the feedthrough pin solder holes 54 from their otherwise naturalresting positions, but this is not problematic. In effect, PCB tab(s)130 force an air gap inside of the IPG case 30 to exist between thesevered traces 108′ and the feedthrough 32, which prevents theirshorting. Thus, PCB tab(s) 130 eliminate the need for additionalinsulation or spacers at the severed edge 114′, and provide a simple andcost-effective solution to isolate severed traces 108′.

As noted earlier, it is preferred that none of the traces 108 passingbetween the extender PCB 104 and the IPG PCB 42 pass through theportion(s) where the PCB tab(s) 130 will be formed. This is because PCBtab(s) 130 may contact the feedthrough 32 as just noted, and thus anysevered traces passing through PCB tab(s) 130 might be shorted. However,traces 108 may pass through the portion 134 outside of the PCB tab(s)130. As shown in FIG. 8, the offset distance used in such portion 134(z) may differ from that used in portion 132 between the PCB tab(s) 130(x), or they may be the same. Because the severed edge 114′ may extendsignificantly beyond the length of the feedthrough 32, such as to theright in FIG. 7, use of a smaller offset distance (z), or indeed nooffset distance, can be used, as shorting of severed traces 108′ is nota concern in such locations.

Other modifications can be made to affect the goal of preventing severedtraces from contacting conductive structures in the IPG. For example, inFIG. 9, which shows another example of IPG PCB 42 after it has beensingulated from the extender PCB 104 portion of its test PCB 102, thesevered edge 114′ defines a PCB recess 140 through which all traces 108pass and are now severed 108′. Because they are recessed by an offsetdistance (e.g., x) from the rest of the severed edge 114′, the severedtraces 108′ should not be at risk of shorting to the feedthrough 32 towhich severed edge 114′ is close and may come into contact. Again, morethan one recess 140 could be used along severed edge 114′.

It should be noted that while the present invention was contemplatedgiven the particular geometry of the IPG 10 in which the severed edge114′ of the IPG PCB 42 is close to the feedthrough 32, severed edgesformed as disclosed herein may run the risk of shorting to anyconductive structures 150 in an IPG or other medical device, such as thecase 30, another PCB, other electrical components or wires, etc. The PCBtab(s) 130 and/or PCB recess(es) 140 can also be used to preventshorting of the severed traces 108′ to such other conductive structures150. Indeed, the disclosed techniques can have applicability outside ofmedical devices.

Although particular embodiments of the present invention have been shownand described, it should be understood that the above discussion is notintended to limit the present invention to these embodiments. It will beobvious to those skilled in the art that various changes andmodifications may be made without departing from the spirit and scope ofthe present invention. Thus, the present invention is intended to coveralternatives, modifications, and equivalents that may fall within thespirit and scope of the present invention as defined by the claims.

What is claimed is:
 1. An implantable medical device, comprising: acircuit board comprising electronic components, the circuit boardcomprising an edge along a side of the circuit board, wherein the edgecomprises a plurality of exposed traces each coupled to a node in thecircuit board, wherein the edge comprises at least one first portioncomprising at least some of the exposed traces, and at least one secondportion not comprising the exposed traces, wherein the at least onefirst portion is recessed with respect to the at least one secondportion.
 2. The device of claim 1, further comprising a conductivestructure proximate to the edge, wherein the at least one second portionis configured to prevent the exposed traces in the at least one firstportion from contacting the conductive structure.
 3. The device of claim2, wherein the at least one second portion is configured to prevent theexposed traces in the at least one first portion from contacting theconductive structure by the at least one second portion contacting theconductive structure.
 4. The device of claim 2, wherein the conductivestructure is perpendicular to a plane of the circuit board.
 5. Thedevice of claim 2, further comprising a case for housing the circuitboard, wherein the conductive structure comprises a feedthrough coupledto the case.
 6. The device of claim 5, further comprising a plurality ofelectrodes, wherein at least some of the nodes in the circuit boardcomprise electrode nodes, wherein each of the electrode nodes is coupledto one of the plurality of electrodes.
 7. The device of claim 6, whereinthe plurality of electrodes are located on at least one lead coupled tothe electrode nodes.
 8. The device of claim 6, further comprising aplurality of feedthrough pins passing through the feedthrough, whereineach of the electrode nodes is coupled to one of the plurality ofelectrodes via one of the feedthrough pins.
 9. The device of claim 1,wherein at least some of the nodes in the circuit board comprisereference voltage nodes.
 10. The device of claim 9, further comprising abattery, wherein a positive terminal of the battery is coupled to one ofthe reference voltage nodes, and wherein a negative terminal of thebattery is coupled to another of the reference voltage nodes.
 11. Thedevice of claim 1, wherein the circuit board comprises a bus, andwherein at least some of the nodes comprise signals of the bus.
 12. Thedevice of claim 1, wherein there are two second portions and one firstportion, wherein the first portion is between the two second portions,and wherein the first portion comprises all of the exposed traces. 13.The device of claim 1, wherein the at least one second portion comprisesat least one tab extending from the edge relative to the at least onerecessed first portion.
 14. The device of claim 1, wherein theelectronic components are configured to implement the functionality ofthe implantable medical device.
 15. The device of claim 1, furthercomprising: a case comprising a feedthrough with a plurality offeedthrough pins; a support structure within the case; an antenna withinthe case affixed to the support structure; and a battery within the caseaffixed to the support structure; wherein the circuit board is withinthe case and affixed to the support structure, the circuit boardcomprising electronic components configured to implement thefunctionality of the implantable medical device, and wherein theantenna, battery, and feedthrough pins are electrically coupled to thecircuit board.
 16. A method for constructing and testing a circuit boardfor an implantable medical device, comprising: coupling electroniccomponents to a circuit board, wherein the circuit board comprises animplantable medical device portion and an extender portion, wherein theextender portion comprises a plurality of traces and a connector with aplurality of contacts, wherein each trace is coupled to a node in theimplantable medical device portion and to a contact of the connector;testing the electronic components via the connector; and singulating theimplantable medical device portion from the extender portion therebyforming a severed edge comprising the traces as severed, wherein thesevered edge of the implantable medical device portion comprises atleast one first portion comprising at least some of the severed traces,and at least one second portion not comprising the severed traces,wherein the at least one first portion is recessed with respect to theat least one second portion along the severed edge.
 17. The method ofclaim 16, wherein testing the electronic components comprises insertingthe connector in a socket of a tester wherein the electronic componentsare configured to implement the functionality of the implantable medicaldevice.
 18. The method of claim 16, wherein at least some of the nodesin the implantable medical device portion comprise electrode nodes eachcoupleable to an electrode of the implantable medical device.
 19. Themethod of claim 18, wherein the implantable medical device portioncomprises a plurality of holes, wherein each hole is connected to one ofthe electrode nodes and is coupleable to a feedthrough pin coupleable toone of the electrodes.
 20. The method of claim 16, wherein the at leastone second portion is configured to prevent the severed traces in the atleast one first portion from contacting a conductive structure.
 21. Themethod of claim 16, wherein the at least one first portion and the leastone second portion are formed during the singulation step by cuttingalong a sever line defining shapes of the at least one first portion andthe least one second portion.